Picture transmission apparatus



L ,1931. LANGMUIR PICTURE TRANSMISSION APPARATUS Filed May 17. 1930 Inventor: lrvi n9 Lahgmui 9 M4700 His Attorney.

Patented Oct. 20, 1931 UNITED STATES .PATENT OFFICE IRVING LANGMUIR, or SCHENEGTADY, new onn, Assienon TO GENERAL nnnc- TRIO comrAN-Y, A conronnrron on NEW YORK I PICTURE TRANSMISSION APPARATUS Application filed Mayl17, 1930. Serial No. 453,367.

My invention relates to picture transmission apparatus and particularly to that .part

of the apparatus by which-the received image is projected. The object ofmy invention is to provide improved receiving apparatus whereby the image produced thereby shall beeither more brilliant or of larger size than heretofore has been obtainable and shall be more sharply defined.

My invention will ,be better understood from the following description taken in cons nection with the accompanying drawing and its scope will be pointed out in the appended claims. Y

In the single figure of the drawing which illustrates one embodiment of my invention, I have shown the light source 1, the screen 2 upon which the image is projected, and the optical system therebetween comprising the collecting lens 3, the rotatable lensdisk 4 having therein the spiral series'of lenses 5 and'the objective 6.- The lens disk is shown mounted on the'shaft of the motor 7 by means of -which it is rotated in synchronism with a corresponding member at the sending station. Various well understood means may be employed for insuring synchronous rotation of the corresponding members at the sending and receivingstations.

The source of light 1 which I employ is an arc lamp of the flaming arc type, a form of such lamp being commonly termed a Beck arc lamp. As is well known, the light from a lamp of thistype comes principally from the incandescent vapors of metallic salts or carbides in the-arc and is far more intense than the light emitted by are lamps of the common or non-flaming type. Inasmuch as the heat loss and hence the rate of cooling of the incandescent'vapor is extremely rapid, the arc is susceptible to modulations up to frequencies as high as 20,000, or more cycles per second, which is sufficiently high for the satisfactory transmission of pictures.

The are lamp 1 may be supplied with current from any suitable source. In thedraw-.

ing, I hav shown it connected by way of example with the D. C. output side of the motor generator 8 through the stabilizing resistance 9. In the connectionl have shown the secondary of the modulating transformer 10 whose prlmary by a connection with the radio receiver 11, having the antenna 12, is adapted to receive'signals transmitted by radio from the sending station. A by-passing condenser 13 is shown inshunt with the generator and the resistance ,9 and a second resistance for limiting oscillations from the arc is shown at '14:.

Inasmuch as the light emitted from the in- -candescent vapor of the flaming-arc 1 is many times brighter than that emitted by the incandescent t ps of the electrodes from which the arc springs, the light spot which is caused to scan the screen by the apparatus above described-is sufficiently well defined to produce a satisfactory image where the requirements are not too exacting. Where a sharper definition is required, I provide means for excluding such light as comes from the lamp electrodes so that light spot on the screen is composed only of light emitted by the incandescent vapor of the are which as has alread been pointed out is capable of. the desired hig frequency modulation. As an example of one means which may be employed for thus excluding the undesirable light, I have shown the disk 15 having the splral series of holes 16 therein which are the same in number and are arranged in correspondence with the lenses in the disk 4. The disk 15 is positioned in the plane of the'focal points of the lenses 5 and is mounted to rotate with the lens disk, for example, by being secured to the motor haft beyond the lens disk. By this arrangement the light emanatingfrom the incandeswfil ends of the electrodes is out 01f by the disk 15 while the light from the highly luminous incandescent vapor of the arc passes freely through the holes in the disk and forms the light spot on the screen.

-What I claim as new and desire to secure by Letters Patent of the United States, is

1. Picture receivin apparatus comprising an arc lamp of the aming arc type, means for modulating the current supplled to the lamp in accordance with the received signal, a

screen, means adaptedto be operated in synchronism with the sending apparatus for proarc of said lamp, and means for excluding from the screen light from the electrodes.

2. Picture receivin apparatus comprising an arc lamp of the fl aming arc type, means for supplying to the lamp operating current modulated in accordance with the received signal, a screen, optical means including a member rotatable in synchronism with the sending apparatus for focusing light from the arc of said lamp in a spot in said screen,

and means for limiting the light reaching v the screen to that emanating from the arc.

3. Picture receiving apparatus comprising an arc lamp of the flaming arc type, means for supplying direct current to said lamp, means or modulating said direct current supply in accordance with signals received from a sending apparatus, a screen, a disk having a series of lenses arranged in a spiral therein and arranged successively to pass between the lamp -and the screen when the disk is rotated, a motor for rotating the disk in s nchronism with a sending apparatus, an 0 jective, and a second disk rotatable with the first mentioned disk and having a series of holes therein corresponding with said lenses for excluding from the objective all light emanating from the electrodes of said Iii witness whereof, I have hereto set in hand this 16th day of Ma 1930.

IRVINiEr LANGMUIR. 

